cc/gcc: do not consume parameters when parsing them

The current construct consumes the parameters while we parse them.
Change this to a construct that does not consume the parameters.

This has no impact on gcc, but is done for homogeneity with other
components (eg. glibc).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Compute s390-specific values

CT_DoArchTupleValues() {

    # That's the only thing to override

    if [ "${CT_ARCH_64}" = "y" ]; then

        CT_TARGET_ARCH="s390x"

    fi

}